Electric heating device and method



Jan. 6. 1925. 1,522,188

A. w. HULL ELECTRIC HEATING DEVICE AND METHOD Filed Nov. 21, 1923 Inventor:

Albert-W Hull, y %;/4WAW His Attorney.

. trical Patented Jan. 5, 1925. UNITED STATES ALBERT w. norm, or

p 1,522,188 PATENT OFFICE.

sormunc'rany, NEW YORK, assionoa ro GENERAL nwo'rtuo company, a coaromr on or NEW YORK.

' HEATING DEVICE AND METHOD.

Application filed November 21, 1928. Serial No. 676,1.

To all whom it may concern:

Be it known that I, ALBERr W. I-IULL, a citizen of the United States, residlng at Schenectad in the county of Schenectady, State of ew York, have invented certain new and useful Improvements in Electric Heating Devices and Methods, of which the following is a specification.

The resent invention relates to the eleceating of a liquid, such as milk, which contains material which is decomposable by heat. When milk which contains emulsified particles of casein and fats is heated by a continuous current, or by an alternating electric current of commercial frequency, a deposition of some of these so-called milk solids upon the electrodes occur which by reason of their relativel high resistivity become overheated and a feet the taste of the milk.

I have discovered that an easil decomposable emulsion such as milk, can e heated emulsion when the direction of current flow is reversed with a sufficient rapidity, as by the application of high frequency current from an electric oscillator. V

The accompanying drawing illustrates somewhat diagrammatically apparatus suitable for carrying out my invention, Fig. 1 showing acontinuous apparatus and Fig. 2, an intermittent apparatus.

Thedrawing shows in Fig.1 a container 1, which consists preferably of a suitable conductive material, such as nickel or tin andconstitutes one pole of an electric circuit. The opposite pole is constituted by an electrode 2, which is constituted by a rod passing through an insulator 3, and being suspended from the cover 4 of the container. An inlet duct 5 and an'outlet duct 6 are pro- .vided for. the circulation of the milk, or other'liquid through the heating chamber. The electrodes 1, 2 are connected by the conductors 7, 8 to a source ofhigh frequency current.

In the drawing the now well-known pliotron or vacuum tube oscillator has been diagrammatically indicated, although other sources of high frequency current may be employed. The vacuum tube oscillator comprises a pliotron tube 10, having the cathode 11 connected to the negative terminal of a direct current source 12, andhaving the anode 13 connected in series with primary 14 of a transformer to the positive terminal.

potential. A tuning con enser 21 is pro- Vided in shunt to the primary 14 of the transformer, and a by-pass condenser 22 is provided across the generator terminals as usual. The high frequency oscillations which are generated are induced in the secondary winding 23 to which-the load circuit 7, 8 is connected.

As. shown in Fig. 2 the high frequency heating may be carried out by a very simple apparatus constituted by cooperating plate electrodes 25, 26 which are connected to the high frequency supply conductors 7, Sand are suspended from an insulatin plate 27. When a'liquid which is apt to e burnt by the ordinary heating methods, for example, chocolate, is to be prepared, the in-.

gredients, that is, milk, sugar, chocolate, etc. are placed in a container 28, conveniently conslstlng of glass or porcelain, the electrodes 25, 26 are lowered into the liquid and a high frequency current is applied until a desired temperature has been obtained.

I have found that when using current of a frequency of about 100,000 cycles per second at a voltage of about 5 to 10 volts, with a sufiicient current, sa about 50 amperes, milk can be heated to t e boiling point in a few seconds without any noticeable coating of *the electrodes. Of course, the articular frequency and volta e which may e used in any given case wil depend on the, conditions. I desire by the appended claims to cover in general the heatmg of liquids containing in suspension or solution materials which are sensitive to heat by electric currents having a frequency so high that deposition does not occur upon the electrodes.

What I claim as-new and desire to secure by Letters Patent of the United States, is

1. The method of heating an emulsion by passage of electric current between electrodes in contact with said emulsion which consists in varying the polarity of said current at-a sufficiently high rate to prevent the deposition of the discontinuous phase of said emulsion upon said electrodes.

2. The method of heating milk by passage of electric current between electrodes which are in electric contact with said milk, which consists in applyin -a current which varies in polarity at a'su ciently high rate to revent substantially the deposition of mil solids u on'said electrodes.

3. The met 10d of heating a liquid containing carbonizable material which consists in conducting high frequency-current therethrough.

4. he method of heating a liquid containing carbonizable material, which consists in bringing said liquid into contact with electrodes connected to an electric circuit and generating in said circuit electric currents of sufiiciently high frequency to prevent adhesion of carbonizable material to said electr'odes 5. An apparatus for heating liquids which are decomposable at high temperature comrising'a container, electrodes therefor makmg contact with the liquidto be heated and means for supplying high frequency to said electrodes.

In witness whereof, I have'hcreunto set my hand this 20th day of November 1923.

. ALBERT \V. HULL. 

